76-61-9

Basic information

• Product Name: Thymol Blue
• Synonyms: TB; Thymolsulfonephthalein; Thymolsulphonephthalein; 4,4'-(1,1-dioxido-3H-2,1-benzoxathiole-3,3-diyl)bis[5-methyl-2-(propan-2-yl)phenol]; 2-{(E)-[4-hydroxy-2-methyl-5-(1-methylethyl)phenyl][2-methyl-5-(1-methylethyl)-4-oxocyclohexa-2,5-dien-1-ylidene]methyl}benzenesulfonic acid
• CAS NO: 76-61-9
• Molecular Formula: C₂₇H₃₀O₅S
• Molecular Weight: 466.5891
• EINECS: 200-973-3
• Product Categories: Sulfonephthalein;Analytical Chemistry;Indicator (pH);pH Indicators
• Mol File: 76-61-9.mol
• Article Data: 0

Chemical Properties

• Melting Point: 221-224℃
• Boiling Point: 539.4°C (rough estimate)
• Flash Point: 36 °C
• Density: 1.229g/cm³
• Refractive Index: 1.599
• Storage Temp.: Store at RT.
• Solubility: 0.11g/l
• PKA: Pka1:1.65(at 25℃)(PH=1.2 to 2.8) Pka2:8.9(at 25℃)(PH=8.0 to 9.6)
• Water Solubility: Soluble in alcohol and dilute alkali solutions. Insoluble in water.
• Stability: Stable. Combustible. Dust may form an explosive mixture with air. Incompatible with strong oxidizing agents.
• Merck: 14,9400
• BRN: 368036
• CAS DataBase Reference: Thymol Blue(CAS DataBase Reference)
• NIST Chemistry Reference: Thymol Blue(76-61-9)
• EPA Substance Registry System: Thymol Blue(76-61-9)

Safety Data

• Statements: 10
• Safety Statements: S24/25:Avoid contact with skin and eyes.
• RIDADR: UN 1170 3/PG 3
• WGK Germany: 3
• RTECS: XP2575000
• TSCA: Yes
• PackingGroup: II
• Hazardous Substances Data: 76-61-9(Hazardous Substances Data)

Usage

Chemical Properties

brown to green powder or crystals

Uses

Different sources of media describe the Uses of 76-61-9 differently. You can refer to the following data:
1. As as acid-base indicator; pH: red 1.2 to yellow 2.8; also yellow 8.0 to blue 9.6.
2. Thymol Blue is a useful pH indicator compound. Dyes and metabolites.

Biochem/physiol Actions

Thymol Blue is a pH indicator, which is yellow/orange at low pH and blue in color at high pH.

Synthetic route

2-sulfobenzoic acid cyclic anhydride (81-08-3) + thymol (89-83-8) → 2-(4-hydroxy-5-isopropyl-2-methyl-benzoyl)-benzenesulfonic acid (861304-71-4) + thymol blue (76-61-9)

Conditions	Yield
With zinc(II) chloride at 105 - 110℃;

thymol (89-83-8) + 2-chlorosulfonylbenzoyl chloride (34684-21-4) → 2-(2-isopropyl-5-methyl-phenoxysulfonyl)-benzoic acid-(2-isopropyl-5-methyl-phenyl ester) + thymol blue (76-61-9)

Conditions	Yield
at 100 - 110℃;

2-(4,4'-dihydroxy-5,5'-diisopropyl-2,2'-dimethyl-benzhydryl)-benzenesulfonic acid → thymol blue (76-61-9)

Conditions	Yield
im Sonnenlicht;

1,1-dioxo-1λ6-benzisothiazol-3-one → thymol blue (76-61-9)

Conditions	Yield
With sulfuric acid Erhitzen der Reaktionsloesung mit Thymol auf 140grad;

thymol (89-83-8) + ammonium salt of/the/ 2-sulfo-benzoic acid → thymol blue (76-61-9)

Conditions	Yield
With phosphorus pentoxide

thymol (89-83-8) + benzoic acid o-sulfonic acid-dichloride → thymol blue (76-61-9)

Conditions	Yield
With zinc(II) chloride at 100 - 110℃;

thymol (89-83-8) + (E)-3-Ureido-but-2-enoic acid ethyl ester (5435-44-9, 22243-66-9) + benzoic acid o-sulfonic acid endo anhydride → 2-(4-hydroxy-5-isopropyl-2-methyl-benzoyl)-benzenesulfonic acid (861304-71-4) + thymol blue (76-61-9)

Conditions	Yield
at 105 - 110℃;

thymol (89-83-8) + dichloride of/the/ benzoic acid o-sulfonic acid → thymol blue (76-61-9) + benzoic acid o-sulfonic acid dithymyl ester

Conditions	Yield
at 100 - 110℃;

2-(4,4'-dihydroxy-5,5'-diisopropyl-2,2'-dimethyl-benzhydryl)-benzenesulfonic acid + water (7732-18-5) + air → thymol blue (76-61-9)

2-(4,4'-dihydroxy-5,5'-diisopropyl-2,2'-dimethyl-benzhydryl)-benzenesulfonic acid + air + alkali → thymol blue (76-61-9)

2-(4-hydroxy-5-isopropyl-2-methyl-benzoyl)-benzenesulfonic acid (861304-71-4) → thymol blue (76-61-9) + 2-sulfo-benzoic acid endo anhydride

2-(4-hydroxy-5-isopropyl-2-methyl-benzoyl)-benzenesulfonic acid (861304-71-4) + (E)-3-Ureido-but-2-enoic acid ethyl ester (5435-44-9, 22243-66-9) → thymol blue (76-61-9) + 2-sulfo-benzoic acid endo anhydride

Conditions	Yield
at 135℃;

thymol (89-83-8) + 2-sulfo-benzoic acid endo anhydride → 2-(4-hydroxy-5-isopropyl-2-methyl-benzoyl)-benzenesulfonic acid (861304-71-4) + thymol blue (76-61-9)

Conditions	Yield
With zinc(II) chloride at 105 - 110℃;

methanol (67-56-1) + thymol blue (76-61-9) → 3,3-bis-(5-isopropyl-4-methoxy-2-methyl-phenyl)-3H-benz[c][1,2]oxathiol-1,1-dioxide

sodium ethanolate (141-52-6) + thymol blue (76-61-9) → 3,3-bis-(4-hydroxy-5-isopropyl-2-methyl-phenyl)-3H-benz[c][1,2]oxathiol-1,1-dioxide ; disodium-compound (62625-21-2)

thymol blue (76-61-9) + acetic anhydride (108-24-7) → 3,3-bis-(4-acetoxy-5-isopropyl-2-methyl-phenyl)-3H-benz[c][1,2]oxathiol-1,1-dioxide

thymol blue (76-61-9) + benzoyl chloride (98-88-4) → 3,3-bis-(4-benzoyloxy-5-isopropyl-2-methyl-phenyl)-3H-benz[c][1,2]oxathiol-1,1-dioxide

thymol blue (76-61-9) + aniline (62-53-3) → 2-(4,4'-dianilino-α-hydroxy-5,5'-diisopropyl-2,2'-dimethyl-benzhydryl)-benzenesulfonic acid-lactone

Conditions	Yield
at 115 - 120℃;

thymol blue (76-61-9) → 2-(4,4'-dihydroxy-5,5'-diisopropyl-2,2'-dimethyl-benzhydryl)-benzenesulfonic acid

Conditions	Yield
With water; zinc

thymol blue (76-61-9) → bromothymol blue (76-59-5)

Conditions	Yield
With bromine; acetic acid

thymol blue (76-61-9) → 2-sulfobenzoic acid (632-25-7) + 2,2'-Methyl-5,5'-isopropyl-4,4'-diphenoquinon

Conditions	Yield
With sulfuric acid; bromate In water at 25℃; for 24h; Rate constant; Mechanism; different H2SO4 conc.; different ionic strength; in the presence of aq. Br2;

water (7732-18-5) + thymol blue (76-61-9) + zinc dust → 2-(4,4'-dihydroxy-5,5'-diisopropyl-2,2'-dimethyl-benzhydryl)-benzenesulfonic acid

bromine (7726-95-6) + thymol blue (76-61-9) + acetic acid (64-19-7) → bromothymol blue (76-59-5)

thymol blue (76-61-9) + disodium-salt of bis-carboxymethyl-amine → 3,3'-bis[N,N-bis(carboxymethyl)aminomethyl]thymolsulfonphthalein (3778-22-1)

Conditions	Yield
With formaldehyd; acetic acid

thymol blue (76-61-9) → difluorothymol blue + monofluorothymolsulfonphthalein + thymolbenzein

Conditions	Yield
With acetic acid for 0.0833333h;	A n/a B n/a C 5 %Chromat.

Upstream product

• 81-08-3 2-sulfobenzoic acid cyclic anhydride 
• 89-83-8 thymol 
• 861304-71-4 2-(4-hydroxy-5-isopropyl-2-methyl-benzoyl)-benzenesulfonic acid 
• 5435-44-9 (E)-3-Ureido-but-2-enoic acid ethyl ester 
• 7732-18-5 water 
• 34684-21-4 2-chlorosulfonylbenzoyl chloride 

Downstream Products

• 3778-22-1 Methylthymolblau 
• 76-59-5 bromothymol blue 
• 632-25-7 2-sulfobenzoic acid 
• 62625-21-2 3,3-bis-(4-hydroxy-5-isopropyl-2-methyl-phenyl)-3H-benz[c][1,2]oxathiol-1,1-dioxide ; disodium-compound